System and method for dynamic control of image capture in a video conference system

ABSTRACT

A system and method are provided for capturing and transmitting frames in a video conference. The method comprises determining a frame rate and a shutter speed according to variable control data, capturing image data according to the determined shutter speed, and transmitting the captured image data through a communication interface to a remote video conference system. The variable control data specifies a relationship between the frame rate and the shutter speed.

RELATED APPLICATIONS

This application claims priority to U.S. Patent Application Ser. No.60/794,016, entitled “VIDEOCONFERENCING SYSTEM,” which was filed on Apr.20, 2006.

TECHNICAL FIELD

This invention relates in general to communications, and moreparticularly to a system and method for dynamic control of image capturein a video conference system.

BACKGROUND

Video conferencing, also known as video teleconferencing, is a form ofvisual collaboration that has existed in some form or another since theintroduction of the television. Primitive forms of video conferencingwere demonstrated with closed circuit television systems using cable.NASA also implemented a primitive form of video conferencing during thefirst manned space flights, using multiple radio links.

Such techniques, however, proved to be too expensive and otherwiseimpractical for more mundane applications, such as business meetings.Video conferencing did not become a viable communication option forthese applications until improvements in bandwidth and compressiontechniques in the 1980s and 1990s enabled practical transmission overdigital networks. Finally, IP-based communication systems emerged as acommon conferencing medium in the late 1990s.

Today, video conferencing applications are spreading throughout thebusiness and healthcare industries, as well as the general public. Theunderlying technology continues to evolve, however, and new processesand systems need to be developed to improve the quality, reliability,and simplicity of this cutting edge communications medium.

SUMMARY

In accordance with the present invention, certain disadvantages andproblems associated with the quality of video conference systems havebeen substantially reduced or eliminated. In particular, the presentinvention significantly improves the quality of video conference systemsthrough a system and method for reducing blur in image capture.

In accordance with one embodiment of the present invention, a method isprovided for capturing and transmitting frames in a video conference.The method comprises determining a frame rate and a shutter speedaccording to variable control data, capturing image data according tothe determined shutter speed, and transmitting the captured image datathrough a communication interface to a remote video conference system.The variable control data specifies a relationship between the framerate and the shutter speed.

In accordance with another embodiment of the present invention, a systemis provided for capturing and transmitting frames in a video conference.The system comprises an image data interface, a communication interface,and a controller coupled to the image data interface and to thecommunication interface. The controller is operable to receive variablecontrol data through the communication interface, capture image datathrough the image data interface according to a variable shutter speedparameter in the control data, and transmit the captured image datathrough the communication interface to a remote video conference system.

An advantage of certain embodiments is the ability of conferenceparticipants to control image capture characteristics of a remoteimaging device. More particularly, conference participants maydynamically adjust image capture parameters to control blur and strobeeffects of images that are captured and transmitted from a remoteconference location. Accordingly, conference participants maydynamically compensate for individual preferences, as well as varyingdegrees of motion by remote participants.

Other technical advantages of the present invention may be readilyapparent to one skilled in the art from the following figures,descriptions, and claims. Moreover, while specific advantages have beenenumerated above, various embodiments may include all, some, or none ofthe enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsadvantages, reference is now made to the following description, taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a simplified block diagram of an endpoint in a videoconference system;

FIG. 2 is a simplified block diagram of a video capture device in theendpoint of FIG. 1; and

FIG. 3 is a flowchart that illustrates an example operation of the videocapture device of FIG. 2.

DETAILED DESCRIPTION

The principles of the present invention may be implemented in a varietyof hardware and software configurations. As is commonly understood inthe art, the structure for implementing the functions described belowmay comprise any appropriately configured data processing hardware,software, process, algorithm, or combination thereof. Moreover, thestructure and functions may be consolidated in a single physical deviceor distributed across many physical devices.

Additionally, certain embodiments are described below with reference toan exemplary network of functional elements. Each such functionalelement may represent a hardware device, software, process, or anycombination thereof. A “network” comprises any number of thesefunctional elements coupled to and in communication with each otherthrough a communications medium. A “communications medium” includeswithout limitation any conductive, optical, electromagnetic, or othermedium through which a functional element can transmit data. Unlessotherwise indicated in context below, all network nodes may use publiclyavailable protocols or messaging services to exchange signals, messages,and other forms of electronic communication with each other through anetwork.

Software and data structures associated with certain aspects typicallyare stored in a memory, which may be coupled to a functional elementdirectly or remotely through a network. The term “memory,” as usedherein, includes without limitation any volatile or persistent medium,such as an electrical circuit, magnetic disk, or optical disk, in whicha data or software may be stored for any duration. A single memory mayencompass and be distributed across a plurality of media.

FIG. 1 is a simplified block diagram of an endpoint 2 in a videoconference system in which the invention may operate. Endpoint 2 isprovided for illustrative purposes only, as the configuration andelements of video conference systems may vary widely. The functionalelements of endpoint 2 may include, without limitation, video capturedevice 4, conference display 6, endpoint controller 8, and userinterface 10. Typically, an endpoint further includes an element foraudio input (e.g., a microphone) and audio output (e.g., speakers).Video capture device 4 represents any imaging device or video inputelement operable to receive image data and produce an image frame, suchas a digital video camera. Conference display 6 represents any videooutput element operable to display images, while user interface 10represents any functional element operable to interact with an end-user(particularly a conference participant).

Endpoint controller 8 represents any functional element operable tocommunicate with other elements of a video conference system, includinglocal elements such as video capture device 4 and remote elementscoupled through a network interface across a network 12. Endpointcontroller 8 generally is operable to establish media sessions with aremote video conference system endpoint across network 12. In certainembodiments, endpoint controller 8 also controls the behavior of userinterface 10 and receives user input from user interface 10. Endpointcontroller 8 may further comprise a codec, which is any functionalelement operable to compress/decompress media streams (including imagedata) associated with a conference.

Certain embodiments of the present invention contemplate operation in anenvironment of a conventional audio and video conferencing system. Otherembodiments, though, are intended to operate in conjunction withconferencing elements designed to provide an experience that simulates aface-to-face conference. For instance, such elements may comprise one ormore high-definition screens of sufficient dimensions to displaylife-size images of conference participants, while audio componentsprovide high-definition surround sound. Such an experience is referredto herein as a “telepresence” conference to convey the concept of aconferencing system that surpasses the quality and experience ofconventional video conferencing experiences.

In general, conferencing systems operate by establishing a media sessionbetween two endpoints, particularly across a network. FIG. 1 may berepresentative of both endpoints, but as already noted, the preciseconfiguration of endpoints may vary widely. Once the endpoints establisha media session, they each employ various elements to capture and conveymedia data, such as audio and video data. The media data is thentransferred between the two endpoints across the network as a mediastream. The receiving endpoint then conveys the media data to conferenceparticipants through an appropriate output device (e.g., conferencedisplay 6). As described below, certain embodiments of the inventionprovide a mechanism for interactively controlling the capture andtransfer of the media data.

FIG. 2 is a simplified block diagram of video capture device 4 in theendpoint of FIG. 1. Video capture device 4 generally comprises a memory14, an image controller 16, and an image capture interface 18. Incertain embodiments, video capture device 4 also may include acommunication interface 20.

In one embodiment, image capture interface 18 comprises a light sensor22 and a shutter (not pictured). The shutter may be a physicalmechanism, or it may be a virtual (or electronic) shutter. Imagecontroller 16 opens a physical shutter to expose light to light sensor22, and closes the shutter to interrupt light reaching light sensor 22.In contrast, image controller 16 may operate an electronic shuttersimply by instructing light sensor 22 to collect image data for a giventime, and then possibly ignore it for a given time. The term “shutterspeed” generally refers to the length of time that light sensor 22collects the image data. Image controller 16 converts light informationfrom light sensor 22 into image data, which is typically stored inmemory 14. Image data representing a single image generally is referredto as a “frame.”

Communication interface 20 represents any functional element operable toconnect to other functional elements for transferring data in digitizedor analog signal form, and may include without limitation an Ethernetinterface, air link, infrared link, serial port, or parallel port.Communication interface 20 may be coupled to a remote endpoint of avideo conference system, either directly or indirectly. As FIG. 1illustrates, communication interface 20 may couple video capture device4 to a remote endpoint indirectly through endpoint controller 8, whichis coupled to network 12. Image controller 16 may receive control datafrom the remote endpoint through communication interface 20, and maytransmit frames through communication interface 20 to a remote endpointfor viewing by other conference participants. The rate at which imagecontroller 16 transmits frames is referred to herein as the “frametransmission rate.” The frame transmission rate may be the same as theframe capture rate. Collectively, the frame transmission rate and theframe capture rate are referred to as the “frame rate.”

Shutter speed generally affects the characteristics of a given image. Inparticular, shutter speed affects “blur” and “strobe” characteristics.Given a certain frame capture rate, for example, a relatively highshutter speed may produce clear images that appear to strobe (i.e. movediscontinuously) when displayed. In contrast, a lower shutter speed mayproduce images that appear continuous, but blurred when displayed. Theseeffects may be compounded even further by rapid motion (i.e. significantchanges between frames). To accommodate varying degrees of motion, aswell as individual preferences of conference participants, variousembodiments of the invention provide a mechanism for dynamicallycontrolling the shutter speed and/or frame rate to adjust these blur andstrobe effects (as described in greater detail below).

FIG. 3 is a flowchart that illustrates an example operation of videocapture device 4 that dynamically controls the shutter speed and/orframe rate during a video conference. In step 100, endpoint controller 8establishes a media session with a remote endpoint. In step 102, imagecontroller 16 receives control data. In step 104, image controller 16processes control data to determine an appropriate shutter speed andframe rate. In step 106, image controller 16 operates the shutter tocapture image data and generate a frame according to the shutter speedand frame rate determined in step 104. In step 108, image controller 16transmits the image data through communication interface 20. Imagecontroller 16 repeats steps 102-108 until determining that the sessionhas been terminated (steps 110-112).

The control data referenced above may represent static, pre-configureddata, or it may represent dynamic control data generated as the resultof end-user actions associated with either image controller 16 or aremote endpoint. For example, image controller 16 or the remote endpointmay by coupled to a user interface having a dial, slide bar, free-forminput field, or the like for an end-user to control the imagecharacteristics. The control data generally comprises variableparameters that determine a relationship between the shutter speed andframe rate (or frame time). In some embodiments, the relationship is theresult of independent parameters, while in others the relationshiprepresents a ratio of one parameter to the other. In one embodiment, forexample, control data comprises an independent or absoluterepresentation of a variable shutter speed and a fixed frame rate (orvice versa). In an alternate embodiment, though, control data mayrepresent a ratio or percentage of shutter speed to frame rate, blur tostrobe, or any other suitable metric.

In certain embodiments, control data may be received throughcommunication interface 20 from a remote endpoint (thereby allowingremote control of image characteristics), or from endpoint controller 8.Alternatively, image controller 16 may retrieve control data from memory14.

Although the present invention has been described with severalembodiments, a myriad of changes, variations, alterations,transformations, and modifications may be suggested to one skilled inthe art, and it is intended that the present invention encompass suchchanges, variations, alterations, transformations, and modifications asfall within the scope of the appended claims.

1. A video conferencing system comprising: a digital video camera; and avideo conference controller coupled to the digital video camera, thevideo conference controller operable to: establish a video conferencesession with a remote endpoint; receive control data from the remoteendpoint, the control data comprising a first plurality of variableparameters that establish a relationship between a frame rate and ashutter speed; generate a plurality of digital video frames from thedigital video camera according to the frame rate and the shutter speed;and transmit the plurality of digital video frames to the remoteendpoint in conjunction with the video conference session.
 2. The videoconferencing system of claim 1, further comprising: a display operableto display video information received from the remote endpoint; and auser interface operable to provide a control to enable selection of asecond plurality of variable parameters, wherein the video conferencecontroller is further operable to relay the second plurality of variableparameters to the remote endpoint to dynamically affect the displayedvideo information in real time in response to selection of the control.3. A method of capturing and transmitting frames in a video conference,the method comprising: receiving control data from a remote videoconference system, the control data comprising a plurality of variableparameters that establish a relationship between a frame rate and ashutter speed; generating a plurality of digital video frames accordingto the frame rate and the Shutter speed; and transmitting the pluralityof digital video frames through a communication interface to the remotevideo conference system.
 4. The method of claim 3, wherein the controldata is received from the remote video conference system through thecommunication interface.
 5. The method of claim 3, wherein the controldata comprises a fixed frame rate input and a variable shutter speedinput.
 6. The method of claim 3, wherein the control data comprises avariable frame rate input and a fixed shutter speed input.
 7. The methodof claim 3, wherein the control data comprises a ratio of the frame rateto the shutter speed.
 8. The method of claim 3, wherein: thecommunication interface is a network interface; the control data isreceived from the video conference system through the network interface;the control data comprises a fixed frame rate input and a variableshutter speed input; and the variable shutter speed input comprises aratio of the frame rate to the shutter speed.
 9. A system for capturingand transmitting frames in a video conference, the system comprising: animage data interface; a communication interface; and a controllercoupled to the image data interface and to the communication interface,the controller operable to: receive control data through thecommunication interface from a remote video conference system, whereinthe control data comprises a plurality of variable parameters thatestablish a relationship between a frame rate and a shutter speed;generate a plurality of digital video frames according to the frame rateand the shutter speed; and transmit the plurality of digital videoframes through the communication interface to the remote videoconference system.
 10. The system of claim 9, wherein the control datafurther comprises a frame rate parameter and a variable shutter speedparameter, and the variable shutter speed parameter is a fraction of theframe rate parameter.
 11. The system of claim 9, wherein the controldata further comprises a ratio of the shutter speed to the frame rate.12. Software for capturing and transmitting frames in a videoconference, the software being embodied in a computer-readable memorycomprising computer code such that when executed is operable to: receivecontrol data from a remote video conference system, the control datacomprising a plurality of variable parameters that establish arelationship between a frame rate and a shutter speed; generate aplurality of digital video frames according to the frame rate and theshutter speed; and transmit the plurality of digital video framesthrough a communication interface to the remote video conference system.13. The software of claim 12, wherein the control data comprises a fixedframe rate input and a variable shutter speed input.
 14. The software ofclaim 12, wherein the control data comprises a variable frame rate inputand a fixed shutter speed input.
 15. The software of claim 12, whereinthe control data comprises a ratio of the frame rate to the shutterspeed.
 16. The software of claim 12, wherein the control data isreceived from the remote video conference system through thecommunication interface.
 17. The software of claim 12, wherein: thecontrol data is received from the video conference system through thecommunication interface; the control data comprises a fixed frame rateinput and a variable shutter speed input; and the variable shutter speedinput comprises a ratio of the frame rate to the shutter speed.
 18. Asystem for capturing and transmitting frames in a video conference, thesystem comprising: means for receiving control data from a remoteendpoint through a network, the control data comprising a plurality ofvariable parameters that establish a relationship between a frame rateand a shutter speed; means for generating a digital video frameaccording to the frame rate and the shutter speed; and means fortransmitting the digital video frame through the network to the remoteendpoint.